Correlative compositional mapping and electronic transport of p-n heterostructured semiconductor nanowires for photovoltaic applications
EMSL Project ID
47607
Abstract
The p-n junction can be regarded as the most important electronic structure that is responsible for the ubiquity of semiconductor microelectronics today and are found in a wide range of devices from microprocessors to solar cells. Efforts to continually scale down the size of electronic components is guiding research to explore the use of nanomaterials synthesized from a bottom-up approach; group-IV semiconductor nanowires being one such material. However, Au-catalyzed synthesis of Si-Ge semiconductor nanowire heterojunctions using the commonly-used vapor-liquid-solid (VLS) growth technique results in diffuse heterojunction interfaces with a magnitude on the order of the nanowire diameter, leading to serious doubts of producing compositionally-sharp p-n junctions using this approach from a Au catalyst. We have recently reported the ability to increase Si-Ge nanowire heterojunction abruptness by VLS synthesis from a Au(1-x)Ga(x) catalyst alloy. Given that control of the heterojunction width between Si and Ge has been established, a driving hypothesis of the proposed research is that growth of a doped p-n heterojunction from the liquid AuGa catalyst should lead to more abrupt doped heterointerface compared to growth from pure Au. The goal of the proposed work at EMSL is to perform an experimental correlative study combining both atom probe tomography (APT) and scanning transmission electron microscopy (STEM), as well as to pursue modeling and simulations of both the growth and minority carrier dynamics of axial p-n heterojunction semiconductor nanowires. The proposed work at EMSL will support a larger effort underway at Los Alamos National Laboratory where we aim to cross-correlate the total dopant distribution and interface morphology measured by APT and STEM, with the measured transport dynamics from photovoltaic devices. The experimental findings will provide a basis for atomistic models of growth and carrier transport calculations performed at EMSL. Ultimately, the correlation between APT, TEM, and modeled and simulated device transport properties will provide a means to understand how the nanowire morphology, total dopant distribution measured from APT, and active dopant distribution estimated from transport studies, all contribute to the observed properties. In this way, we can begin to truly understand how the observed electronic properties are manifested from the measured concentration and distribution of dopants across a p-n heterojunction relevant to photovoltaic material applications.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2012-10-01
End Date
2014-09-30
Status
Closed
Released Data Link
Team
Principal Investigator
Co-Investigator(s)
Team Members
Related Publications
Gamalski AD, DE Perea, J Yoo, N Li, MJ Olszta, RJ Colby, DK Schreiber, C Ducati, ST Picraux, and S Hofmann. 2013. "Catalyst Composition and Impurity-dependent Kinetics of Nanowire Heteroepitaxy." ACS Nano 7(9):7689-7697. doi:10.1021/nn402208p
Gan Z, DE Perea, J Yoo, Y He, RJ Colby, JE Barker, M Gu, SX Mao, CM Wang, ST Picraux, DJ Smith, and MR Mccartney. 2016. "Characterization of Electrical Properties in Axial Si-Ge Nanowire Heterojunctions Using Off - Axis Electron Holography and Atom-Probe Tomography." Journal of Applied Physics 120(10):Article No. 104301. doi:10.1063/1.4962380
Justin G. Connell, KunHo Yoon, Daniel E. Perea, Edwin J. Schwalbach, Peter W. Voorhees, and Lincoln J. Lauhon, Identification of an Intrinsic Source of Doping Inhomogeneity in Vapor−Liquid−Solid-Grown Nanowires, Nano Letters, 13, 199-206 (2013)
Le ST, P Jannaty, X Luo, A Zaslavsky, DE Perea, SA Dayeh, and ST Picraux. 2012. "Axial SiGe Heteronanowire Tunneling Field-Effect Transistors." Nano Letters 12(11):5850-5855. doi:10.1021/nl3032058